Moistening tobacco for stemming



Oct. 15, 1940. BAER 2,217,934

MOISTENING TOBACCO FOR STEMMINE Filed Oct. 7, 1937 jive/Z307 1-7 0727?fifiaer g; Z6295; XM am; M W.

Patented Oct. 15, 1940 UNITED STATES MOISTENING TOBACCO FOR STEMMINGJohn M. Bacr, Chicago, Ill., assignor to The Guardite Corporation, acorporation of Illinois Application October 7, 1937, Serial No. 167,858

Claims. (Cl. 131-140) This invention relates to a method of stemmingtobacco and more particularly to a method of treating dry brittletobacco to render it soft and, pliable and then stemming the material 5while still in a soft pliable condition.

In the present tobacco treating methods, tobacco is stored in largehogsheads in which from 1,000 to 1,600 lbs. or so of tobacco are heldunder very considerable pressure. When the storage period is over, thistobacco is in an extremely dry and brittle condition and can not behandled without considerable breakage. As a result, it has beenuniformly customary to moisten this tobacco in a steam or ordering room,in which the moisture content of the tobacco is increased from 2 to 3%,and its temperature slightly raised. A dry tobacco normally has amoisture content of from "I to 9%, which is therefore raised to around10 to 12% 20 in the ordering treatment.

The so-treated tobacco is then satisfactory for grading, but themoisture content is not sufllcient so thatthe material can beimmediately put through stemming machines. Instead, the hogsheads arebroken down and the material'placed on conveyers, which carry it througha steam tunnel or ordering chamber, wherein the moisture content isfurther increased, and from which the tobacco is immediately passed tostemming 30 machines, whereinit is stemmed.

It has now been discovered that if the moisture content of tobacco isincreased initially to approximately 15 to 17%, it may be then directlystemmed without the use of the steam 3.3 tunnel. Such a process hasenormous advantages in the saving of expense and also in avoiding thelosses of aromatic materials by distillation in the steam tunnel.

The invention is illustrated diagrammatically ".gfiin the drawing inwhich: I0 represents a vacuum chamber provided with doors H, a steamline I2, a water line I3, and an evacuating line It. A hogshead oftobacco l5 may be placed inside the vacuum chamber and treated ashereinafter described.

, In accordance with this invention, dry tobacco, having say a moisturecontent of 9%, is treated in the hogsheads with steam and liquid watersuflicient to raise its moisture content to 15 to 17%.

In carrying out the process, the bulk tobacco is placed in a gas-tightchamber and subjected to a high vacuum, suflicient to reduce thetemperature of the tobacco considerably. Normally, a vacuum of below 29is necessary for this purpose. After the tobacco has been substantiallyfreed in this manner from non-condensible gas, steam and liquid waterare admitted to the vacuum chamber, the liquid water being preferablyintroduced in spray form at the high 5 vacuum. In this way the water hasbeen found to penetrate to the center of the tobacco without raising itstemperature as much as the steam does. During the first portion of thesteaming period, it is preferred to continue evacuation, 10 this havinga flushing efi'ect upon any remnants of non-condensible gas in the tankor any that may be introduced with the steam or water..

The admission of the steam will, of course, raise the temperature andpressure in the chamber, and it is preferred to stop the steamingoperation before the temperature has reached a deleterious point. Thiswill, of course, vary for different tobaccos, but it is preferred not toexceed about 175 F. for Burley tobacco and 160 F. for Virginia'tobacco.

The amount of moisture added is controlled by the amount of wateradmitted, and also by the increase in temperature. The amount which maybe added in any one operation, however, is limited to about 10 to 12%.If more is desired, a further watering cycle may be employed.

Liquid water is preferably only admitted during a portion of thesteaming operation, the steaming being continued and the temperatureraised for a substantial period after the admission of liquid water hasceased. This additional steaming operation is preferred, because ittends to remove any wet spots which may have been produced by unequalspraying of the water. Preferably steam used in this portion of theprocedure is slightly superheated.

With some tobaccos it is desirable, following the operation heretoforedescribed, again to lower the pressure in the chamber to produce boilingof water. This second evacuation apparently removes traces ofnon-condensible gas, which may have been held in very tightly compressedportions of the hogshead, or in portions where the vapor pressure wasextremely low, or it may remove non-condensible gas which has beenbrought in by the incoming steam or water that has collected in thecenter of the hogshead. This second evacuation preferably reduces thetemperature at least 10 to 15 and is preferably fol- -lowed by asteaming operation to bring the temperature 'up materially, preferablyto approximately the temperature existing before the second evacuationtreatment.

The hot tobacco, which preferably has from 2 to 3% more moisture in itthan is necessary in the stemming operation, is then removed from thevacuum chamber and promptly passed to the stemming machine, which may beof any conventional type, such as the Pasley stemmer.

In the transfer from the vacuum chamber to the stemmer, the tobaccopasses through the open air and is materially cooled by contacttherewith and by evaporation of the excess moisture.

It is preferred that the tobacco be hot when it is freed from the vacuumchamber, because. for a given moisture content, tobacco is more pliablewhen warm than when cold. Moreover, since some of the cooling in the airis done by contact with the air and by radiation, there is not as muchloss of moisture as there would be in the chamber where practically theentire temperature drop must be due to evaporation of moisture.

As an example of the process, a hogshead of Kentucky Burley tobaccoweighing 1,213 lbs. and having an initial temperature varying from 81 atthe center to 83 F. near the outside, was placed in a vacuum chamber andevacuated until the temperature of the tobacco had fallen to 68 F.throughout. This took a period of about 20 minutes and the absolutepressure reached about'0.3". Steam was then admitted for 14 minutes toraise the temperature in the tobacco to approximately 164 F., and then avacuum was again drawn to reduce the temperature to approximately 134 F.at the center of hogshead. This took about 10 minutes and the mercuryindicated a pressure of approximately 3.9" at the end of the evacuationcycle. Steam was then again admitted to bring the temperature up to 164F.

In the first steaming period of this operation, 20 gallons of water weresprayed into the tank with the steam during the first 2 minutes of thesteaming period. The last 12 minutes of the steaming period were withsteam only.

The last steaming period required only about 7 minutes, or a total of 51minutes for the entire operation. Evacuation was continued for the first3 minutes of the firststeaming cycle.

During this operation, 91 lbs. of water, or approximately 7.5% byweight, was added to the hogshead. The hogshead was free from cold ordry spots and was in satisfactory condition.

In another example of the process, Virginia tobacco in a hogsheadweighing 1,178 lbs. and having a temperature of 81 F. at the center wassubjected to a vacuum suflicient to produce a temperature of 68 F. inthe center. This required about 20 minutes and the barometer at the endof the period was approximately 0.38" absolute. Steam was thenintroduced with 20 gallons of water for 2 minutes, and the steamingoperation continued for 3 minutes further. The

chamber was then evacuated for 10 minutes and then steam was admittedfor 13 minutes, to produce a temperature of approximately 150 F. in thecenter of the hogshead. Tobacco was then evacuated again until itstemperature had dropped to F. after 10 minutes, and was then steamed for9 minutes to produce a temperature of 157 F.

At the end of this time the tobacco had gained 89 lbs. in weight, orsomewhat more than 7%.

The tobacco was in excellent condition for handling and was free fromdry spots.

Tobacco treated by this process not only completely passes directly tothe stemming machines, but when stemmed produces pliable stems asdistinguished from the frequently brittle stems resulting from sweatroom plus ordering chamber operations.

The foregoing detailed description is given for clearness ofunderstanding only, and no unnecessary limitations should be understoodtherefrom.

I claim:

1. In a tobacco treatment process, the successive steps of subjectingthe tobacco to a high vacuum, supplying a mixture of steam and water inmist form to the tobacco whereby the absolute pressure thereon isincreased from the initial vacuum value to a higher but sub-atmosphericpressure, and then subjecting the tobacco to an increased vacuumsufiicient to cause evaporation of moisture therefrom whereby thetobacco is cooled.

2. In a tobacco treatment process, the successive steps of subjectingthe tobacco to a high vacuum, supplying to the evacuated tobacco steamand finely divided water vapor entrained therewith, the amount of waterso supplied being in excess of an amount sufficient to saturate thesteam supplied at the subatmosperic pressures prevailing and thensubjecting the tobacco to an increased vacuum suflicient to causeevaporation of moisture therefrom, whereby the tobacco is cooled.

3. A process for treating tobacco comprising subjecting the tobacco to ahigh vacuum, supplying to the tobacco a mixture of steam and waterwhereby the absolute pressure on the tobacco is increased and moistureis added thereto, and re-evacuating the tobacco sufficiently to causeevaporation oi some of the moisture therefrom.

4. A process for treating tobacco comprising subjecting the tobacco to ahigh vacuum, supplying to the evacuated tobacco steam and finely dividedwater entrained therewith, the amount of water so supplied being inexcess of an amount suflicient to saturate the steam supplied at thesub-atmospheric pressures prevailing, increasing the vacuum on thetobacco suiliciently to cause evaporation of moisture from the tobaccowhereby the tobacco is cooled.

5. In the bulk treatment of organic products,

the successive steps of removing from the product substantially allnon-condenslble gas, supplying thereto a mixture of steam and water, thewater being in mieromist form, and being supplied to the product in acarrier of steam, whereby the steam carries the particles of watersubstantially uniformly throughout the bulk of the product andcondensestherein, leaving the water distributed therethrough, and then subjectingthe product to an increased vacuum sumcient to cause evaporation ofmoisture therefrom, whereby the product is cooled.

JOHN M. BAER.

